1. Field of the Invention
The present invention relates to a disk drive, and more particularly, to a noise reducing apparatus for a disk drive which can effectively reduce noise generated from the inside of the disk drive and dissipated to the outside thereof.
2. Description of the Related Art
Hard disk drives (HDDs), which are data storage devices used for computers, use read/write heads to reproduce or record data with respect to a disk. In the HDD, the read/write head performs its functions while being moved by an actuator to a desired position in a state of being lifted to a predetermined height from a recording surface of a rotating disk.
FIG. 1 is an exploded perspective view illustrating the configuration of a conventional hard disk drive. Referring to FIG. 1, a conventional hard disk drive includes a base member 11. On the base member 11, a spindle motor 30 rotates a disk 20 and an actuator 40 moves a read/write head, which records and reproduces data, to a desired position on the disk 20.
The actuator 40 includes a swing arm 42 rotatably coupled to a pivot bearing 41 installed on the base member 11. The actuator 40 includes a suspension 43 installed at one end portion of the swing arm 42 and supporting a slider having the head mounted thereon toward a surface of the disk 20 to be elastically biased, and a voice coil motor (VCM) 45 to rotate the swing arm 42. The voice coil motor 45 is controlled by a servo control system to rotate the swing arm 42 in a direction following the Fleming's left hand rule by the interaction between a current applied to a VCM coil and a magnetic field generated by a magnet. That is, when the power of the hard disk drive is on and the disk 20 starts to rotate, the voice coil motor 45 rotates the swing arm 42 counterclockwise to move the head toward a position above a recording surface of the disk 20. When the power of the hard disk drive is off and the disk 20 stops rotating, the voice coil motor 45 rotates the swing arm 42 clockwise so that the head is moved out of the disk 20.
A cover member 12 is assembled to the base member 11 by using a plurality of screws 19. The cover member 12 protects the disk 20 and the actuator 40 by encompassing the same so as to prevents intrusion of dust or moisture into the inside of the disk drive and a propagation of noise from the inside of the disk drive to the outside thereof. The cover member 12 includes a groove 13 to reduce the vibration of the disk 20 by reducing the interval between the disk 20 and the cover member 12. A circulation filter 50 to filter particles inside the disk drive is provided at one corner of the base member 11.
FIG. 2 is a sectional view illustrating the route along which noise is transferred in the conventional disk drive. Referring to FIG. 2, noise is generated when the disk 20 rotates at a high speed and the actuator 40 performs a read/write/seek function. The noise generated in the disk drive is dissipated outwardly through the base member 11 and the cover member 12 as indicated by the wavy lines (representing noise). Such noise can be classified into structural-borne noise and an air-borne noise based upon the transfer route. The structural-borne noise is generated by the rotation of the spindle motor 30 and is transferred to the base member 11 to be dissipated outwardly. The air-borne noise is generated by a change in the pressure of fluid (that is, air) during the vibration of the disk 20 and the rotation of the disk 20. The air-borne noise is transferred to the cover member 12 and dissipated to the outside of the disk drive.
Conventionally, since ball bearings are mainly used for the spindle motor 30, the structural-borne noise is generated by the vibration generated due to defective ball bearings and has taken the most portion of noise generated in the disk drive. Thus, the structural-borne noise transferred to the base member 11 is reduced by attaching a damping member 60 on the outer surface of the base member 11. Recently, fluid dynamic bearings (FDB) have been increasingly used for the spindle motor 30 as the rotation speed of the disk drive and the track per inch (TPI) of the disk 20 increase. Accordingly, in the disk drive, while the structural-borne noise is decreased, the portion of the noise attributed to the air-borne noise increases. As a result, the use of the damping member 60 does not provide a great effect on the reduction of noise in the disk drive.